1. Field of the Invention
The present invention relates generally to Ethernet Passive Optical Network (EPON) communications.
2. Background Art
A Passive Optical Network (PON) is a single, shared optical fiber that uses inexpensive optical splitters to divide a single fiber into separate strands feeding individual subscribers. An Ethernet PON (EPON) is a PON based on the Ethernet standard. EPONs provide simple, easy-to-manage connectivity to Ethernet-based, IP equipment, both at customer premises and at the central office. As with other Gigabit Ethernet media, EPONs are well-suited to carry packetized traffic.
Existing EPON Optical Line Terminals (OLTs) implement an EPON MAC layer. The EPON MAC layer provides various packet processing capabilities, quality of service (QoS) functions, and management features.
To ensure maximum leverage of EPON MAC features, it is desirable that the EPON MAC is used end-to-end from the OLT to the ONU. This means that standard defined EPON MAC data rates (1 Gbps or 10 Gbps) must be used between the OLT and the ONU. In practice, however, the physical medium between the OLT and the ONU (which may include a hybrid fiber coaxial network, for example) may not always sustain full EPON MAC data rates. There is a need, therefore, to sub-rate an EPON. MAC communication link for upstream or downstream traffic.
The present invention will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.